Feature

Climate science update

Meteorologists contributing to a new international report on climate change are now more certain than ever that humans are causing climate change.

Increased occurences of severe weather such as super storms are expected with climate change.

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Scientists are more convinced than ever before that humans are causing climate change. That information is not going to be a surprise to many Green Lifestyle readers, but late last year it was formalised in a report from some of the world’s most eminent meteorologists belonging to the Intergovernmental Panel on Climate Change (IPCC).

When the IPCC released its latest report during a conference in Stockholm, Sweden, climate change deniers were quick to downplay its implications. But having drawn on millions of scientific observations over the past six years, and being written by 209 lead authors and 50 review editors from 39 countries, there’s more than enough substance to their findings to warrant great care and urgency on the part of governments in deciding what action to take.

The IPCC is jointly sponsored by the World Meteorological Organisation (WMO) and the United Nations Environment Programme. A statement by WMO Secretary General Michel Jarraud concluded: “This report… should serve as yet another wake-up call that our activities today will have a profound impact on society not only for us but for many generations to come.”

Jarraud said WMO findings confirmed that many weather extremes of the past decade were unprecedented. “The decade 2001–2010 was the warmest on record, continuing a trend of pronounced global warming,” he continued. “More natural temperature records were broken than any other previous decade. The rate of temperature increase would have been even higher if it were not for the relative cooling influence of La Niña events, and the role of the deep oceans in absorbing heat. The IPCC report demonstrates that we must greatly reduce global emissions in order to avoid the worst effects of climate change.”

The implications
The IPCC provides governments with “actionable information” at regional level. Its scientists have improved climate models since their last report in 2007, allowing them to better understand the causes and impact of climate change. Here’s a summary of some of the report’s main points:

- Each of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850. Though the rate of increase slowed in the last decade, this should not be considered in isolation as the last ten years are still the hottest on record.

- Global surface temperatures could increase by 0.9°C to 5.4°C by the end of the 21st century, and more than likely by more than 2°C. World governments have already agreed to try to keep temperature increases to 2°C by cutting carbon emissions. They’re aiming for five per cent cuts by 2020.

- It’s likely that human influence has more than doubled the probability of occurrence of heatwaves in some locations.

- As oceans warm, and glaciers and ice sheets reduce, global average sea level will continue to rise, but at a faster rate than we have experienced over the past 40 years. The report states with high confidence that Arctic sea ice decreased in the period 1979–2012 with a rate that was very likely in the range 3.5 to 4.1 per cent per year, resulting in a likely rise of 28 to 82 cm by 2100.

- The atmospheric concentrations of the greenhouse gases carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) have all increased since 1750 due to human activity. In 2011 the concentrations of these gases exceeded pre-industrial levels by about 40 percent, 150 per cent and 20 per cent respectively.

- There’s a high confidence that climate change will affect carbon cycle processes in a way that will spur the increase of CO2 in the atmosphere. Further uptake of carbon by the ocean will increase ocean acidification.
- There is high confidence that sustained warming greater than some threshold would lead to the near-complete loss of the Greenland ice sheet over a millennium.

- Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions but effects will persist for many centuries even if emissions of CO2 stop.

Australian action
In applying key findings of the report to local conditions, the Australian Conservation Foundation’s climate change program manager, Tony Mohr, said Australia’s hottest days could be almost six degrees hotter. “It was 47 degrees on Black Saturday. What happens when the thermometer hits 53?,” he said. “The southwest of Western Australia faces an 80 per cent increase in the number of drought months. In Victoria, 44,600 homes become vulnerable to flooding from the combination of sea level rise and extreme storm surges. The list of examples is almost endless, and it simply highlights the importance of Australia retaining a price on pollution and strong limits on pollution.”

Australian Federal Minister for the Environment, Greg Hunt, says the government is committed to cutting carbon emissions by five per cent by 2020, but reiterated in a statement on the IPCC report that keeping the former Labor government’s carbon price was not the way to go about it.

The Liberal government’s scrapping of the independent Climate Change Commission immediately upon gaining office didn’t inspire confidence in the government’s attitude toward dealing with climate change. Green Lifestyle will have more on the Federal Government’s work in this area in upcoming issues as developments occur.

What is clear, in the words of UN Secretary General Ban Ki Moon, is that “we know the nature of the problem and the options for addressing it”. “The heat is on,” he said. “Now we must act.”